Preventive Medicine Column

Dr. David L. Katz

As reliably as the other signs of seasons turning comes CDC’s annual shift in focus to influenza.  The prevailing vaccine strains have been identified, and the yearly customization of vaccine to correspond has been completed.  Manufacturers have begun shipping vaccine doses to clinicians.

This year, as every year, I will roll up my sleeve and get vaccinated.  This year, as every year, I recommend you do the same.  And this year, as every year, I know some of you will decline this recommendation, and some will even denigrate it.   (No, I don’t have a stake in vaccines sales!)

Anti-vaccine sentiment is seemingly pervasive in our culture, and at a minimum, ardent and vocal. Somehow I have wound up on an emailing list that drops anti-vaccine commentary into my inbox on a daily basis.

I can sympathize with the perspectives that underlie vaccine opposition. When bad things, such as autism, happen, everyone wants a reason, and something to blame. There is the hope and belief that nature is the constant house of healing power and benevolent wisdom, kinder and gentler in its ways than science. There are the sinister implications of science in the service of conspiracy theories, the cultivation of dark mischief in veiled corners.

One may sympathize with all this, and still disagree. Disagree, I do.

The strongest argument against immunization is that it represents science interfering with a natural, native balance. The notion is that our immune systems can handle the job without outside interference.  The trouble with the “just leave it to nature” platform is that the nature in question- the nature to which our immune systems are adapted- is long, long gone. It does not exist today, and it has not existed for millennia.  The biological norm for Homo sapiens is life in small, roving, isolated bands.

There are some very important biological implications of small, roving, isolated bands. Small roving bands do not propagate highly virulent pathogens, because being highly virulent in a small population is the fast track to extinction. There is an advantage up to a point in genes that make germs good at getting from one person to the next, invading, and infecting. Making someone sick is advantageous, too- because while the attendant misery is incidental, coughing and sneezing are great means of transmission. A germ that makes us cough and sneeze is actually enlisting our assistance in getting a fast pass to the person 3 feet away.

But the genes that make bugs good at making us sick can, of course, go further- and make the bugs lethal. That is a bad end for both host and pathogen in a small roving, band- because when the people die, the bugs are left with nowhere to go, and they die, too. The genes that make germs good at suicide don’t tend to last very long.

All of this changed roughly 12,000 years ago at the dawn of agriculture and human civilization, and the rise in population density. In large, concentrated human populations- bugs can get away with being lethal. Small pox, bubonic plague, and influenza can kill huge numbers of us and still thrive- because there are huge numbers of us to kill. In a population of billions, the death of millions is inconsequential- except, of course, to the millions concerned. In a population of billions of hosts, small pox, influenza, measles, mumps, rubella, and polio can wreak havoc, and flourish just the same.

What this all means is that arguments for an “au naturel” approach to our concourse with pathogens are, in a word, nonsense. A native relationship with microorganisms is an “in for a penny, in for a pound proposition.” We can’t possibly go native without going back to the conditions of our hunter-gatherer ancestry. There is nothing native about a human population in excess of 7 billion.

In modern context, the evidence in support of vaccines is overwhelming. We have eradicated smallpox, and come close to doing the same with polio. Those inclined to be blasé about these stunning public health advances are limited to the beneficiaries of them. Populations subject to the ravages of smallpox and polio fully appreciate what it means to be rid of them. That the debunking of any meaningful link between vaccination and autism falls on deaf ears does nothing to alter the epidemiologic truth. Immunization does not cause autism.

The flu vaccine is far from perfect.  It can fail to prevent flu, and there can be rare complications.  But it usually does prevent flu, and complications of the flu itself are more common by literal orders of magnitude.  Stated bluntly, I think we should focus on the epidemiology-and stop flu-ing around.




Dr. David L. Katz